RomRaider

Hey all,

Months back I got an 03 Wrx with a blown motor, and logically went the cheap route with an emissions pull, ej206 from a JDM TT legacy. At the time I wasn’t as knowledgeable about Subaru stuff or tuning as I am now, and didn’t take notice to this motor having a 9:1 CR, instead of my usdm motor’s 8:1.

From day one I’ve had a knarly misfire above 60% throttle, contributed it to wrong plug gap, coils, clogged injector etc. I’ve now done all of those, brand new, step colder NGK’s, new coils, new injectors-stock 440’s.

Now I’ve figured out, after taking HP Academy, that the compression ratio is very likely the cause.

Hours of searching RR’s stock rom list, trying to find a stock rom from a jdm car using this motor, to no luck, I’m here to ask rom raider community.

Anybody know where to find the base map for a 9:1 CR?

Better yet- the car has: Cold air intake, silicone Turbo inlet, catless upipe, downpipe, mid, and axle back, I have a Grimmspeed EBCS that I haven’t installed yet- so if you have a tune you’ve made with similar mods that’ll work too, just something I can start with and tweak a bit to learn how to tune these- not comfortable enough yet to go through my entire ignition table.

Appreciate your time!

-Mason

I can guarantee that the higher compression will not be causing a misfire. As for tuning all else being equal the higher compression engine will likely be running less ignition advance and might be more sensitive to the amount of boost you are able to run depending on the octane of fuel that is available to you and of course there are other variables as well. It would be nice to see the map you are running and some logs if possible. Also does this JDM engine have AVCS? You must understand that subarus are not as forgiving as other platforms when it comes to getting away with bolt on parts not affecting driveability. You listed a whole bunch of mods, if you are running a different engine and all those mods on a stock map then that is your number one problem.

So yeah the mods are definetely part of the problem, but i dont see any of them causing misfires to this extent, and i intend to tune for them- this motor in this car is my test mule, it has a crack in the case where it mates to tranny, seller sent another one for free, so if i blow it up not the end of the world- perfect to learn to tune.

The motor does not have avcs.

I'm going to attach several things: The stock usdm map i had on the car, then the map i have derived by using a jdm wrx's ignition and fueling table, again i know there's loads of other tables i should edit, but solely for the sake of finding the misfire before i go doing back to back WOT pulls, i threw it on.


I flashed this new tune, and the misfire was almost impossible to recreate, had to go WOT from 2-2500 rpms, but if above 3-3500 it wouldn't happen.

Thinking that this fueling table was based for higher octane fuel, i added some octane booster, and the best 91 i could find, and now i do not have a misfire at all, WOT from any speed or rpm, not a blip, without a wideband this of course scares me, but by the stock 02 sensors readings, im never dipping below 12 or above 14 on WOT....

Along with the maps, are two WOT pulls, one with the misfire, and one now without.

Would love ylur input, and if you can explain my exact problem, would love to tip a few dollars your way for your time.

-Mason

It is difficult to see anything useful in the log, the log is really short and in second gear. Also the factory upstream sensor is almost useless as a tuning tool, It is vital that you invest in a wideband oxygen sensor not only is it a tuning tool but could be used for diagnostics, you specifically need it because you have an aftermarket intake and you need to scale the maf tab in order to be able to hit your fuel target values. Without this vital data its kinda hard to tell if your fuel mixture could be causing a stumble/spark blowout, your logs show af sensor one pegged at .75 lambda when you could actually be way lower than that which could potentially cause a stumble. With that said try the attached map and give it a feeler. I set boost to wastegate pressure if its better than you can introduce some boost but I wouldn't recommend going any further without a wideband, even if you don't care if the engine pops.

[/quote]
It is difficult to see anything useful in the log, the log is really short and in second gear. Also the factory upstream sensor is almost useless as a tuning tool, It is vital that you invest in a wideband oxygen sensor not only is it a tuning tool but could be used for diagnostics, you specifically need it because you have an aftermarket intake and you need to scale the maf tab in order to be able to hit your fuel target values. Without this vital data its kinda hard to tell if your fuel mixture could be causing a stumble/spark blowout, your logs show af sensor one pegged at .75 lambda when you could actually be way lower than that which could potentially cause a stumble. With that said try the attached map and give it a feeler. I set boost to wastegate pressure if its better than you can introduce some boost but I wouldn't recommend going any further without a wideband, even if you don't care if the engine pops.[/quote]


Awesome ill flash that on on my way to work today and see if it helps at all. Ill take another log, i went second to fourth in that last log, ill do the same in this, do you just view logs in excel or is there some way im not aware of in logger? Really appreciate you help!

It is difficult to see anything useful in the log, the log is really short and in second gear. Also the factory upstream sensor is almost useless as a tuning tool, It is vital that you invest in a wideband oxygen sensor not only is it a tuning tool but could be used for diagnostics, you specifically need it because you have an aftermarket intake and you need to scale the maf tab in order to be able to hit your fuel target values. Without this vital data its kinda hard to tell if your fuel mixture could be causing a stumble/spark blowout, your logs show af sensor one pegged at .75 lambda when you could actually be way lower than that which could potentially cause a stumble. With that said try the attached map and give it a feeler. I set boost to wastegate pressure if its better than you can introduce some boost but I wouldn't recommend going any further without a wideband, even if you don't care if the engine pops.[/quote]


So yeah threw that map on, and misfire is completely gone, one slight blip at about 4500 rpms from full throttle.
So this would make me think the the measured air in was actually much less than what the maf was scaled for, so thus the fueling mixture was way to rich, and blowing out the spark, is this about what your thinking?

Ive attached a log from this map, it should be about 20mph, 2nd gear to 80 in 4th. If you have any further suggestions id lvoe to hear them, youve been a major help, this map seems like a good spot to start, i should be able to step by step work through turning it up once i get this wideband installed, i just wanted to figure this out and make sure it wasnt something mechanical, really seems like it isnt, although im sure i need another set of plugs with how rich it has been running...

Appreciate ya

It is possible that it is too rich. But again without a wideband its hard to say. I would get a wideband and scale the maf and go from there. Also always log ignition advance multiplier, feedback knock correction, fine learning knock correction. Also log throttle opening angle. When scaling the maf you will need to do 3rd gear pulls because 1st and 2nd gear will not give you enough useful data to do maf scaling. Also tuning boost is usually done in 3rd gear as well. If you tune for a boost curve in 2nd gear then you will overshoot in 3rd and higher gears. Once you get a wideband I would be glad to help with maf scaling.

In mine opinion. Reference to your log.
You run low ignition timing. Increase ignition timing across all table (or at least at max torque).
Also watch your plug gap.

If you installed a JDM engine without AVCS, did you swap out the Crankshaft and Camshaft pulleys? This must be done for the JDM engine to run with a USDM ECU. If the engine did have AVCS, You would not need to swap out the pulleys.

Haven't been checking this thread so sorry for the delayed reply.

I did swap cam gears, and 02-05 in the states never had avcs, you lucky basta*** got that amazing ej207 over there and got a 2.0 with avcs and higher quality heads all around, we are stuck with these dime-a-dozen ej205's.

AlexMarty's map he sent me helped, but later down the line, it started to come back. I pulled the motor, refreshed some stuff, sent the heads to the machine shop- three cylinders had exhaust valves not sealing. The plug gap was all over the place don't know how because I set them, it helped but 1000 miles in the missing came back.
---This was at the 6-month mark of covid, and from working in the auto parts industry I've come to believe that NGK must have temporarily switched manufacturing, and it's possible that they would expand greatly with heat.

All back together- no issues in the last 12k miles, running Carberry 4.2, going to slap a 20g, 1050x, and TGV deletes on there this weekend and boost it to the moon, I'm dead set on seeing holes in the block.

Again, appreciate your help, AlexMartynyuk, I would definitely like to take o=you up on help scaling the maf, if you could point me to a good forum/page/video on the process of doing that, and I might interrogate you at some point in the process if your willing...

Thanks again ya'll!

-Mason

Nah, USDM. I blew the stock non-avcs 2.0 after running it low on oil around a clover leaf 4 weeks before I quit my job, moved halfway across Missouri, and started on a degree.
I picked up an AVCS ej205 from Jdmracingengines.com. I have actually bought 2 from them. (when comparing to stock tunes, accidentally saved the stock tune and blew it in boost) Also, this is my personal opinion from my experience, those guys have excellent customer service and I did not hesitate to purchase another engine from them




Be sure to purchase your plugs from a reputable dealer. I bought some "NGK Iridumb" from amazon and ebay which both turned out to be poor bootlegs from china. I didn't find this out until after the porcelain broke (all recovered luckily).

Glad to hear up are up and going.